A method is known in which a film is obtained employing an atmospheric pressure plasma discharge processing method using a mixed gas of a rare gas and a film forming gas (see, for example, Patent Document 1). In this method, so far, when a low cost gas other than a rare gas, for example, oxygen, nitrogen or carbon dioxide in air, is used as a discharge gas, strength of electric field (hereinafter referred to also as electric field strength) becomes high and a stable discharge have not been fully easy to obtain under a conventional high frequency electric field. Accordingly, a stable film forming have not been fully easy.
Also, disclosed is a method in which a stable film forming is attained by obtaining a stable discharge using a superposed electric field of a pulsed high frequency electric field and a pulsed direct current electric field under a discharge gas of argon (see, for example, Patent Document 2).
However, these conventional methods have not been fully satisfactory in obtaining a high quality metal oxide film when a production rate is increased. For example, when a metal oxide film of TiO2 or SiO2 was formed on a substrate, adhesiveness between the film and the substrate degraded with time or when a transparent conductive film formed of a metal oxide doped with a metal was prepared, a satisfactory low resistivity tends not to be obtained. Also, thus obtained transparent conductive film was found to exhibit a low etching rate. Another problem has been a higher production cost due to the use of a rare gas, for example, argon as a discharge gas.
(Patent Document 1) Japanese Patent Publication Open to Public Inspection (hereafter referred to as JP-A) No. 2000-303175
(Patent Document 2) JP-A No. 2002-110397
The present invention has been aimed to overcome these problems. An object of the present invention is to provide a film forming method and a substrate having thereon a film produced by the film forming method, the film forming method attaining at least one of the following aspects:
1. Forming a high quality film with a high production rate; and
2. Forming a film with a low production cost.